The invention relates to an arrangement for generating amplitude-modulated, ultrasonic transmission pulses. An arrangement of this type is used preferably for generating transmission pulses with a small frequency spectrum and, in particular, with a low side-lobe level in order to achieve better detection of doppler-shifted echo signals.
Such an arrangement is known in an embodiment comprising a linear amplifier, connected to a high-power, fixed-frequency oscillator and driven with a control voltage of a suitably selected amplitude behaviour to obtain amplitude modulation of the oscillator output voltage. This arrangement has the disadvantage that it becomes complicated and costly if it is required to generate high power, ultrasonic transmission pulses in accordance with a predetermined amplitude behaviour with sufficient accuracy.